Try to cut down Browser/TabContents header dependencies.

chrome/common/page_transition_types.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/common/page_transition_types.h"
 
+#include "base/logging.h"
+
+// static
+PageTransition::Type PageTransition::FromInt(int32 type) {
+  if (!ValidType(type)) {
+    NOTREACHED() << "Invalid transition type " << type;
+
+    // Return a safe default so we don't have corrupt data in release mode.
+    return LINK;
+  }
+  return static_cast<Type>(type);
+}
+
+// static
 const char* PageTransition::CoreTransitionString(Type type) {
   switch (type & PageTransition::CORE_MASK) {
     case 0: return "link";
     case 1: return "typed";
     case 2: return "auto_bookmark";
     case 3: return "auto_subframe";
     case 4: return "manual_subframe";
     case 5: return "generated";
     case 6: return "start_page";
     case 7: return "form_submit";
     case 8: return "reload";
     case 9: return "keyword";
     case 10: return "keyword_generated";
   }
   return NULL;
 }